the autonomic nervous system

The autonomic nervous system

Xiaoming Zhang

The autonomic nervous system

• Introduction:

• Compositions: 1. Visceral sensory nerve 2. Visceral motor nerve 3. Centers of visceral nerves

• The visceral motor nerves: 2 parts: sympathetic and parasympathetic nerves

The sympathetic nervous system:

1. lower center: in lateral horn of T1(or C8) ~ L3 segments of spinal cord (intermediolateral nucleus) 2. peripheral part: sympathetic trunks sympathetic ganglia sympathetic plexuses sympathetic nerves communicating branches

The sympathetic trunk:

--- paravertebral ganglia and interganglionic branches --- extends from the base of skull to the coccyx --- on the both sides of vertebral column --- 5 parts: cervical part (superior, middle and inferior cervical ganglia) thoracic part (10~12 pairs of thoracic sympathetic ganglia) lumbar part (3~4 pairs of lumbar sympathetic ganglia) sacral part (4~5 pairs of sacral sympathetic ganglia) coccygeal part (1 unpair of coccygeal ganglion)

The sympathetic ganglia: 2 types

---- paravertebral ganglia

---- prevertebral ganglia: celiac ganglia,

aorticorenal ganglia

superior mesenteric ganglia

inferior mesenteric ganglia

The communicating branches: --- link the sympathetic ganglion with the corresponding spinal nerve. ---- 2 types: white and gray communicating branches

• white communicating branches sympathetic preganglionic fiberse arise from the neurons of lateral horn from T1~L3 segments of spinal nerves. about 15 pairs via the anterior roots of corresponding spinal nerves to

communicate with the paravertebral ganglia.• gray communicating branches

sympathetic postganglionic fiberse arise from the neurons of the paravertebral ganglia and communicate with the 31 pairs of spinal nerves.

3 ways of termination of sympathetic preganglionic fibers

(the white communicating branches):

1. Some fibers terminate in the corresponding ganglion and make

relay.

2. Some fibers pass upward or downward in the sympathetic

trunk (form the interganglionic branches) to terminate in

above or lower paravertebral ganglia of the sympathetic trunk

and make relay.

3. The other fibers pass through sympathetic trunk to form some

splanchnic nerves and terminate in prevertebral ganglia.

---- greater splanchnic nerve ---- lesser splanchnic nerve

3 ways of termination of sympathetic postganglionic fibers: 1. To form the gray communicating branches and run backward to corresponding spinal nerve to peripheral blood vessels, sweat glands and arrectores pilorum. 2. To surround the arteries as a layer of nerve plexus and innervate the organs which supplied by the branches of those arteries. 3. To terminate directly in certain organs by independent sympathetic nerves.

The parasympathetic nervous system:

1. Lower centers: cranial portion---- 4 pairs of parasympathetic nuclei in brain stem sacral portion---- sacral parasympathetioc nucleus of S2~4 segments of spinal cord 2. Peripheral part:

cranial portion----

E-W nucleus----parasympathetic preganglionic fibers (via oculomotor nerve)----ciliary ganglion (relay)----parasympathetic postganglionic fibers (short ciliary nerves)---- supply the ciliary m. and sphincter pupillae

superior salivatory nucleus----parasympathetic preganglionic

fibers(via the facial nerve )----greater petrosal nerve----

pterygopalatine ganglion (relay)----parasympathetic

postganglionic fibers (via the maxillary—zygomatic – lacrimal

nerves)---- supply the lacrimal gland

superior salivatory nucleus----parasympathetic preganglionic fibers (via facial n.– chorda tympani – lingual n.)---- submandibular ganglion(relay)----parasympathetic postganglionic fibers----supply the submandibular and sublingual glands

Inferior salivatory nucleus----parasympathetic preganglionic fibers (via glossopharyngeal n.– tympanic n. – lesser petrosal n.) ---- otic ganglion (relay) ---- parasympathetic postganglionic fibers(via auriculotemporal n.) ---- supply parotid gland

dorsal nucleus of vagus n. ---- parasympathetic preganglionic

fibers (via the vagus n. and it’s branches) ---- ganglia in organs

(relay) ---- parasympathetic postganglionic fibers ---- supply the

organs of neck, thorax and abdomen (above the left colic flexure).

The sacral portion of parasympathetic nervous system: sacral parasympathetic nucleus ----parasympathetic

preganglionic fibers (via corresponding sacral nerves ---- 3

pelvic splanchnic nerves ---- pelvic plexus and it’s branches ) ---

ganglia in organs (relay) ---- supply the pelvic organs,

descending and sigmoid colons and rectum.

The visceral sensory nerves: